1. Field of the Invention
The present invention relates to a paper magazine for image recording devices such as printers.
2. Background Arts
A printer for printing an image of a negative film on a photosensitive material such as photographic papers generally pre-loads a paper magazine, which contains a roll of photosensitive material wound around a paper tube. The photosensitive material is drawn from the paper magazine, cut into an intended size, and transported to a printing section. The photosensitive material with an image printed is sent to a subsequent developing apparatus.
This kind of paper magazine is disclosed in the Japanese patent laid-open publication No. 07-114108, in which the paper magazine has a drive roller rotated by a drive source in the printer main body and a nip roller facing the drive roller to nip the photosensitive material therebetween so as to transport the photosensitive material.
In order to improve a transport stability, the nip roller may nip the photographic paper with high pressure. However, the high nip pressure possibly causes pressure-induced fog or bears nip impressions on the photosensitive material. This problem may be solved by a paper magazine with several pairs of nip rollers, which can reduce the pressure from individual nip rollers while providing sufficient degree of nip pressure in its entirety. Meanwhile, the paper magazine of the Japanese patent laid-open publication No. 07-114108 has a pair of nip rollers to steadily transport the photosensitive material.
To change the size of the photosensitive materials, the above described printers require a replacement of the paper magazine itself with another containing the photosensitive material of the intended size. If a leading end of the photosensitive material remains out of the paper magazine during the replacement, the leading end will be exposed. This is the reason the drive roller is rotated backwards as the print operation completes, rewinding the photosensitive material back in the paper magazine to protect the photosensitive material from exposure during the replacement.
Since the drive roller and the nip roller always stay in line contact with the photosensitive material in the width direction thereof, leaving the paper magazine unused for a long time will result in bearing a linear impression on the leading end of the photosensitive material. In addition, one or both of these rollers may be deformed because these rollers have soft, rubber-made surfaces. Long-term use of the paper magazine, at the same time, will have an affect on the drive roller and the nip roller to decrease frictional resistance in some part of their surfaces due either to adhesion of paper dust from the photosensitive material, deformation of the roller surface as described above, and degradation of the surface materials. This condition fluctuates feeding force of the drive roller and leads to an error in feed length of the photosensitive material, causing some disadvantages such as unsuccessful setting of the photosensitive material in a cutting position. Further, the drive roller and the nip roller are disposed to nip the side edges of the photographic paper, and such a configuration produces a significant amount of paper dust from the side edges and therefore aggravates the above described disadvantages.